Depolarizing agent for dry batteries and process of making same



UNITED STATES PATENT OFFICE.

CARLETON ELLIS, OF MONTCLAIR, NEW JERSEY, ASSIGNOR, BY MESN'E ASSIGNMENTS, T0 NATIONAL CARBON COMPANY, INC., 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

DEPOLARIZING AGENT FOR DRY BATTERIES AND PROCES-S OF MAKING SAME.

No Drawing.

To all whom it may concern: 7

Be it known that I, CARLE'roN ELLIs, a citizen of the United States, and a'resident of Montclairfin the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Depolarizing Agents for Dry Batteries and Processes of Making Same, of which the following is a specification.

This invention relates to a process of making manganese dioxid substantially or entirely free from manganites thereby yielding a product suitable as a de olarizing agent for dry batteries of the eclanch type and relates particularly to a finely-divided black precipitate of manganese dioxid containing relatively small amounts of water of hydration or being entirely free therefrom which may be prepared in the manner set forth below.

In the oxidation of many of the compounds of manganese in the manganous condition only a partial conversion of manganese dioxid is secured ranging in some cases from 40 or 50% to 70 or 80% under other conditions. Often a portion of the man ganese dioxid unites with some of the manganous material to form a manganous manganite which is quite resistant to further oxldation so that if the conditions are such that the product is formed even very drastic oxidation treatment does not yield a productdof a high percentage of manganese di 0x1 According to the present invention a product containing at least 95% of manganese dioxid and normally 98 to 99% is obtained. This product is preferably secured by simultaneously reacting on a manganous compound with two or more oxidizing agents, for example, nitric acid and hypochlorous acid or sodium hypochlorite and nitric acid. A mixture especially suited for such reaction is manganous nitrate and sodium hypochlorite which when heated to boiling in fairly concentrated solution yield a black precipitate of manganese dioxld substantially free from manganites and which contains about 95% MnO Manganous nitrate when heated alone produces manganese dioxid but not i n so pure a state as that obtained by the ]O1nt action of hypochlorite. While it is not necessary to have one oxidizing agent com- Specification of Letters Patent.

Application filed October 31, 1917. Serial No. 199,424.

bined with the manganous base itis preferable and manganous nitrate, chlorate and the like is suitable for this purpose.

An illustration of one method of carrying out the invention is as follows:

5 parts by weight of manganous nitrate (6H O) was dissolved in 20 parts of water and 10 parts of a 30% solution of sodium hypochlorite was added. This mixture was heated to boiling and an abundant precipitate of black manganese dioxid containing over 95% MnO (a small amount of water of hydration was present) was obtained. In another case the hypochlorite was added in successive portions, and the manganese dioxid formed was filtered off after each addition. The product contained approximately a like content of Mn(),. A portion of the dioxid obtained by this process was boiled for a few minutes with a 10% solution of sulfuric acid. Practically no manganese was dissolved. The product exhibited medium conducting properties.

In another case manganese nitrate (hydrated) was melted in its own water of hydration until it began to decompose forming manganese dioxid or a body containing the latter. A concentrated solution of sodium hypochlorite was added slowly, the rate of addition being such as to keep the volume of the solution constant. The reaction was very violent. The manganese dioxid produced was filtered off and was found to be of high purity.

Some of the material obtained in this manner exhibits a peculiar lag or hysteresis of electrical conductivity.

If a column of manganese dioxid prepared according to the present invention is connected in series with a lamp and a source of potential, a considerable time will elapse before the current through the circuit rises to its full value, as indicated by the fact that the lamp will light (a sufficient potential being employed) but only after a lapse of time. If commercial hydrated manganese dioxid of approximately the same degree of purity is tested in a similar way, it ma also indicate a slight lag in conductivity, but in the case of the material heretofore known, the lag, measured in seconds, will be less than one-third of that exhibited by my novel product, according to measurements which have been made. In some may take place at 100 described product, but in general, it is about one-twelfth as great.

The product obtained by such powerful oxidation or efi'ect of this duplex oxidizing agent may, if desired, be treated in some cases by extraction with an acid such as dilute nitric acid to remove any residue of acid soluble material, iron, etc., or successive extraction with nitric and then with sulfuric acid may be employed. The product is then well washed and dried. The drying C. or higher in order to eliminate as far as possible any free or combined water.

The invention involved herein embraces a new product, namely a depolarizing agent consisting of or comprising a higher oxld of manganese compound or material preferably in the form of a black precipitate containing at least 95% MnO in a slightly hydrated condition and of medium conductivity for the electric current and in the preferred form manifesting a slight lag or hysteresis of conductivity which is d1fierent from ordinary mineral manganese dioxid (pyrolusite) or artificial normally-hydrated artificial manganese dioxid which conduct the electric current Without noticeable lag.

What I claim is:

1. The process of making manganese dioxid substantially free from manganites which comprises heating manganous nitrate in the presence of sodium hypochlorite.

2. The process of making manganese dioxid substantially free from manganites which comprises heating manganous nitrate in the presence of a hypochlorite.

3. The process of making manganese dioxid which comprises heating a compound of manganese and nitric acid in the presence of a hypochlorite.

4. The process of making manganese dioxid substantially free from manganites which comprises reacting on manganous nitrate with sodium hypochlorite.

5. The process of making manganese dias h the herein-- of manganous nitrate with an added oxidiz ing agent. 7

6. he process of making man anese dioxid containing over 95% Mn which comprises boiling a solution of manganous nitrate and sodium hypochlorite, in collecting the precipitate, washing and extracting the residue with dilute nitric acid and finally washing the acid. extracted residue with dilute sulfuric acid.

7 The process of making manganese dioxid which comprises boiling a solution of manganous nitrate and sodium hypochlorite, in collecting the precipitate, washing andJ 1 extracting the residue with dilute nitric aci 8. The process of making manganese dioxid which comprises boiling a concentrated solution of manganous nitrate and sodium hypochlorite, in collecting the precipitate and washing the latter.

9. The process of making manganese dioxid which comprises adding to a boiling solution of manganese nitrate successive portions of sodium hypochlorite, and collecting and washing the precipitate.

10. As a new product higher oxid of manganese depolarizing material, a finely-divided black precipitate containing at least- 95% Mn 2 and possessing a substantially greater conductivity lag than pure hydrated magganese dioxid depolarizers heretofore use 11. A depolarizing agent comprising precipitated slightly hydrated manganese material containing over 95% MnO and possessing a conductivity lag at least three times as great as the ordinary pure hydrated manganese depolarizer.

12. A depolarizing agent comprising precipitated slightly hydrated manganese material containing over 95% MnO and possessing a conductivity lag of a greater order of magnitude than ordinary pure hydrated MnO depolarizer.

GARLETON ELLIS. 

